The present invention relates to an organic-inorganic hybrid glassy material obtained from materials used in a sol-gel method as starting materials, and a production process of the same.
Polymer materials and low melting point glasses have been well known in the art as a material that is softened at 600° C. or lower and have been used in such various fields as sealing material, passivation glass and glaze. The polymer material and the low melting point glass are different from each other in various properties and have been used in different purposes, depending on environments, in which they can be used. In general, the glasses have been used in the case where heat resistance and airtightness capability are in preference, and organic materials represented by the polymer materials have been used in the case where other characteristics than heat resistance and airtightness capability are in preference. Along with the recent advance in technology, other characteristics that have not been demanded receive attention, and materials having such characteristics are expected to be developed.
Under the circumstances, polymer materials that are improved in heat resistance and airtightness capability and glasses having a lowered softening range, i.e., so-called low melting point glass, are actively developed. In the market of electronic materials, in which heat resistance and airtightness capability are demanded, particularly, the low melting point glasses represented by PbO—SiO2—B2O3 glass and PbO—P2O5—SnF2 glass is becoming an essential material in the field of sealing and covering electronic parts. The low melting point glass is low in energy required for production and shaping, which brings about reduction in production cost, as compared to high melting point glass, and therefore, it conforms to the recent social request of energy saving. Furthermore, in the case where it can be melted at a temperature, at which an organic substance having optical functionality is not broken, it can be expected to be used in such an application as a host of an optically active organic substance-containing (nonlinear) optical material in an optical information communication device, such as an optical switch. Accordingly, such a material that has heat resistance and airtightness capability, which are characteristics of ordinary molten glass, and tends to obtain various properties like polymer materials is demanded in various fields, and in particular, low melting point glass receives growing anticipation. Moreover, organic-inorganic hybrid glass receives attention as one kind of the low melting point glasses.
As the low melting point glass, for example, Tick glass, such as Sn—Pb—P—F—O series glass (see P. A. Tick, Physics and Chemistry of Glasses, Vol. 25, No. 6, pp. 149-154 (1984)), is well known in the art, which has been used in limited fields of market owing to the glass transition point thereof at about 100° C. and to the excellent water resistance thereof. However, the low melting point glass contains lead in the major constitutional components, and therefore, it is necessarily replaced with other materials according to the recent trend in environmental protection. Furthermore, the characteristics demanded in the low melting point glasses represented by Tick glass are widely changing, and simultaneously, the demands therefor are also diversified.
As an ordinary production process of glass, the melting method and the low temperature synthesizing method have been known. The melting method is such a method that glass raw materials are melted by direct heating to be vitrified. Many kinds of glass are produced by this method, and the low melting point glass is also produced by this method. In the case where the low melting point glass is produced, however, there are many limitations in glass composition, for example, lead, alkali, bismuth and the like are necessarily included for lowering the melting point.
In the amorphous bulk low temperature synthesizing method, on the other hand, the sol-gel method, the liquid phase reaction method and the non-aqueous acid-base reaction method are being considered. In the sol-gel method, a metal alkoxide or the like is subjected to hydrolysis and polycondensation and treated at a temperature exceeding 500° C. (as described in K. Kamiya, S. Sakka and N. Tashiro, Yogyo Kyokaishi, vol. 84, pp. 614-618 (1976)), generally from 700 to 1,600° C., to obtain a bulk body. In the case where the bulk body produced by the sol-gel method is considered as a practical material, however, it is liable to be a porous material due to decomposition and combustion of organic substances, such as an alcohol, introduced upon preparation of the raw material solution, evaporation emission of a decomposition gas of the organic substance or water through the heating process, which brings about problems in heat resistance and airtightness capability. Accordingly, there are many problems in the bulk production by the sol-gel method, and in particular the low melting point glass has not yet been produced by the sol-gel method.
The liquid phase reaction method has such a problem that it is of low productivity. In addition, hydrofluoric acid or the like is used in the reaction system, and it is limited to production of thin films. Therefore, it is practically substantially impossible to use as a method for producing bulk bodies.
The non-aqueous acid-base reaction method is a method being developed recently, by which organic-inorganic hybrid glass as one kind of the low melting point glass can be produced (as described in M. Takahashi, H. Niida and T. Yokoo, New Glass, vol. 17, pp. 8-13 (2002)), but the method is under development and cannot produce all kinds of the low melting point glass.
Under the circumstances, many kinds of the low melting point glass have been produced by the melting method rather than the low temperature synthesizing method. Therefore, the glass composition is limited due to the operation of melting the glass raw materials, and the kinds of the low melting glass that can be produced thereby are considerably restricted.
The low melting point glass is currently an important material owing to the heat resistance and the airtightness capability thereof, and there are many cases where demanded features are submitted as those for the low melting point glass as a representative. However, the material is not limited to the low melting point glass, and there is no particular problem in a low melting point material or low softening point material other than glass if it meets the demanded features.
There are such known techniques as the production process of quartz glass fibers by the sol-gel method (as described in JP-A-62-297236), the production process of titanium oxide fibers by the sol-gel method (as described in JP-A-62-223323) and the production process of a semiconductor-doped matrix by the sol-gel method (as described in JP-A-1-183438). There are also such known technique as the P2O5—TeO2—ZnF2 series low melting point glass produced by the melting method (as described in JP-A-7-126035) and the organic-inorganic hybrid glass precursor composition and the hybrid glass produced therewith (as described in JP-A-2-137737).
Many kinds of the low softening point material, particularly the low melting point glass, have been produced by the melting method. Therefore, the glass composition is very limited, and the kinds of the low melting glass that can be produced thereby are considerably restricted due to the operation of melting the glass raw materials.
In the case where it is produced by the sol-gel method of the low temperature synthesizing method, on the other hand, a treatment temperature of 500° C. or higher is required for densification. However, no low melting point glass can be obtained at that temperature, and as a result, low melting point glass excellent in heat resistance and airtightness capability could not be obtained. Particularly in the field of electronic material, such low melting point glass has not been available that can be used under severe requirements in heat resistance, airtightness capability and lower melting temperature. Furthermore, low melting point materials other than a glass that satisfies the heat resistance and the airtightness capability have not found either so far.
The methods disclosed in JP-A-62-297236, JP-A-62-223323 and JP-A-1-183438 succeeded in producing materials that had been produced only at high temperature melting, at low temperature, but cannot produce the low melting point glass. Furthermore, a treatment at 500° C. or higher is required after the sol-gel method. JP-A-7-126035 discloses a method capable of producing a glass having a glass transition point of three hundreds and dozens degrees centigrade. However, there has been no instance where a glass having a glass transition point thereunder is produced by using no melting point lowering material, such as lead and bismuth. Moreover, it is uncertain in the method disclosed in JP-A-2-137737 as to the degree of lowering melting point of bulk-form glasses.
Accordingly, such glass that simultaneously satisfies the severe heat resistance and airtightness capability and the low melting point characteristics could not be produced by the conventional production processes. Even materials other than glass have not satisfied such characteristics.
Furthermore, there has been no such glass that simultaneously satisfies the heat resistance and airtightness capability and can be colored or be fluorescently colored. There has been no material other than glass that satisfies such characteristics.